Hi, I have this problem: I had to install the new NOOBS system 2.4.2 on RPI3. During the mono installation, 4.6.2 installed, which does not work with my weather station WH1080. How to get back to version 3.2.8? I am a layman in these matters - I am asking for help or instructions on how to do it. Currently, my station is not working. Very, please help.

»VI« is a "dino" and not a "normal" texteditor. To add text with "VI" in a file is it not enough to put the curser in the line.
- Start with »$ sudo vi mono-xamarin.list«
- then press "i" (it enables the input mode)
- then "type in" (it is the easiest way and don't use "ctrl+c" and "ctrl+v") the needed information »deb http://download.mono-project.com/repo/debian wheezy / snapshots / 4.0.5 main« in this line
- to save the file press "ESC" and then press "w!"
- done

vi is very powerful but can be tricky and unintuitive when you start using it. There are other editors available which are more like the ones on Windows. But Linux itself has quite a learning curve, you can’t expect to use it without learning about it. Fortunately there are lots of learning resources out there.

Frank G, can you help me?
I do not get any edit so that I can write "and" something to enter and esc and "finish". Would you give advice to look quickly through TeamViewer? or step by step guide me through all this. Mono 4.6.2 is installed all the time. I know that I am doing something wrong but I do not know at what moment.

What's next?

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I don't know what error "E325" is but I would go ahead and press return. If the filecontent is OK, than continue with the install procedure. If the filecontet not OK, delet the file and create the file new.
And, like Steve wrote, you can use another editor to edit this file if you are not familiar with VI.
- Frank